'Sense of urgency'
"Let me be clear - 'complete and correct' means complete and correct"
Christopher Hill, US envoy to North Korea nuclear talks
Hill, who represents the US at six-party talks, said on Wednesday the talks were at a "critical, challenging'' point.
"There is some sense of urgency,'' he told a congressional hearing.
"Let me be clear - 'complete and correct' means complete and correct. This declaration must include all nuclear weapons, programmes, materials and facilities, including clarification of any proliferation activities."
North Korea says it gave a complete list of its nuclear programmes to the US last November, but the US said it was incomplete.
Hill said that the US would be willing to re-establish diplomatic ties with North Korea if it completely gave up its nuclear activities.
US experts are currently in North Korea overseeing the disablement of the facilities at the Yongbyon nuclear complex, where plutonium was
produced and believed to have been used to make a nuclear bomb that
Pyongyang exploded in October 2006.
Washington has refused to take North Korea off a US terrorism blacklist until negotiators have the nuclear list.
"While Pyongyang denies a programme of uranium enrichment and they deny their proliferation activities, we believe North Korea continues to engage in both"
Mike McConnell, US director of national intelligence
Meanwhile, a US intelligence report on Tuesday said that North Korea is still pursuing a uranium enrichment capacity.
Mike McConnell, US director of national intelligence, told a congressional hearing he had "moderate confidence" that the North was still pursuing uranium enrichment, as it had in the past.